Interpretive Summary: Analyzing DNA of the fungal pathogen that causes peanut rust (Puccinia arachidis), we determined the presence of a bacterium (Pantoea ananatis) that was described in the past “feeding on spores” of rust fungi. This is the first report of the bacterium being present in peanut rust samples collected from Georgia fields. This is relevant for various reasons. First, because Pantoea ananatis has been described as a potential biocontrol agent of rust diseases. Second, because the bacterium has also been reported as pathogen in maize. And third, because if using urediniospores of Puccinia arachidis to test resistance to rust in peanut cultivars, the potential presence of bacteria needs to be taken into account, as it could compromise the viability of the spores being used.

Technical Abstract:
Peanut rust is caused by the fungus Puccinia arachidis. This disease, if not treated can cause severe damage and defoliation. While sequencing DNA of urediniospores of the rust fungus, BLAST analysis detected many sequences corresponding to the bacterial species Pantoea ananatis. This bacterium, was previously named Erwinia uredovora, to describe it capability to feed on uredospores of rust fungi. Plating of Puccinia arachidis urediniospores collected from Georgia fields showed the bacterium was present in large quantities. This is relevant for various reasons. First, because Pantoea ananatis has been described as a potential biocontrol agent of rust diseases. Second, because the bacterium has also been reported as pathogen in maize. And third, because if using urediniospores of Puccinia arachidis to test resistance to rust in peanut cultivars, the potential presence of bacteria needs to be taken into account, as it could compromise the viability of the spores being used.